The present invention is directed to a dressing, particularly for wounds, which comprises an absorbent substrate and a discontinuous coating of a composition having an ointment-like feel. The dressing is useful for absorbing bodily exudates, particularly wound exudates, and for dispensing active ingredients, for example, therapeutics, to the skin with no substantial loss of absorption capacity. The dressings of the invention and bandages derived therefrom may be easily and comfortably removed from the skin when desired without re-traumatizing a wound site.
Bandages and wound dressings typically comprise an absorbent pad to absorb exudate from a wound. The absorbent pad is typically constructed of a fibrous nonwoven material. One problem with such absorbent bandages is that the fibers of the absorbent pad may become embedded in the healing wound, making it difficult to painlessly remove the bandage without traumatizing the wound. To overcome this problem, absorbent pads used in bandages are typically covered with a porous plastic film to prevent the pad from sticking to the wound.
It is common practice to treat wounds with ointment-like compositions. Ointments are often used because they tend to act as salves that soothe the wound.
Furthermore, ointments may be compounded with active ingredients such as antibiotics to provide therapeutic properties to assist in infection control and wound healing. Because ointments are usually viscous liquids or semi-solids rather than solid materials, therapeutic materials present in an ointment are usually readily available to the wound merely by contact of the wound with the ointment, even in the absence of wetness such as moist wound exudate.
After treatment with an ointment, wounds are typically covered with an adhesive bandage. The use of an ointment in conjunction with a bandage is also beneficial because the ointment tends to prevent the fibers of an absorbent pad present in a bandage from becoming attached to the wound site. While effective at promoting wound healing, a problem with such treatment regimens is that they are relatively inconvenient and messy.
An advancement in the art of wound treatment was the development of structured occlusive dressings of the type described in U.S. Pat. No. 5,814,031, which is incorporated herein in its entirety by reference. The dressings of the ""031 patent comprise a support material and an occlusive composition overlying the support material. Exemplary support materials described in the ""031 patent include woven, knitted and nonwoven fabrics. While these support materials may have some absorptive capacity, the presence of the occlusive composition overlying the support material tends to block the support and prevent it from absorbing moisture-containing fluids such as wound exudate.
Japanese Laid Open Patent Application 56-2909 discloses an adhesive drug material that is administered in the form of a poultice or drug patch. The adhesive drug material is applied to an air-permeable base material in the form of spots, nets or lines, by, e.g., a printing method. The application of the adhesive drug material to the base material in a discontinuous pattern is said to prevent maceration damage to the skin. However, the use of an adhesive material in the wound area of a wound dressing would be expected to be undesirable because contact of the wound with an adhesive composition would be expected to re-traumatize the wound when the dressing is removed.
UK Patent GB 2,221,620 discloses a hemostatic wound dressing material of a fibrous substrate having a discontinuous coating of an aqueous solution of an alginate material deposited on the surface thereof. The final step in the manufacture of the dressing is evaporating the water from the alginate solution, as, for example, by passage of the dressing material through temperature controlled ovens. While the dressings disclosed in the ""620 patent may possess good hemostatic properties, they are not expected to have the soothing properties of ointment-containing dressings. Furthermore, any actives present in such dressing would not be expected to be readily available to a wound without moisture such as that which is contained in wound exudate.
U.S. Pat. Nos. 4,166,108 and 4,331,653 disclose compositions in the form of a lotion or cream to curtail bleeding of the skin. It is stated that these compositions may be impregnated into pre-packaged bandages. Impregnation of these compositions into bandages would again be expected to block the absorptive capacity of the bandages, and would thus prevent the bandages from absorbing wound exudate.
U.S. Pat. No. 5,147,339 discloses wound treatment dressings comprising corpuscles containing bioactive substances in a hydrophilic medium dispersed in a solid, hydrophobic, water insoluble continuous matrix. Because the active substance is distributed in a solid matrix, it is expected that wound exudate or other moisture-containing substances would be required to release the bioactive substance from the matrix and into contact with the wound. Furthermore, the ""339 dressing would not be expected to have the wound soothing properties of ointment-containing dressings.
It is an object of the present invention to provide a dressing for treating wounds that can be removed easily from a wound site when desired without retraumatizing the wound.
It is another object of the invention to provide a dressing that has a soothing effect on wounds.
It is another object of the invention to provide a dressing that is capable of delivering active therapeutic ingredients to a wound site.
It is another object of the invention to provide a dressing that is capable of delivering multiple therapeutic ingredients to a wound site, even when such ingredients are not mutually compatible.
It is another object of the invention to provide a dressing that is capable of absorbing wound exudate.
It is another object of the invention to provide a dressing containing a soothing ointment-like composition while being capable of absorbing wound exudate.
It is another object of the invention to provide a dressing that exhibits all or a combination of the aforesaid attributes.
It is another object of the invention to provide a dressing with the aforesaid attributes in the form of an adhesive bandage.
Additional objects will become evident in the ensuing description of the invention.
The dressings of the invention comprises at least two components:
a. an absorbent substrate having a first skin-facing surface and a second opposing surface; and
b. a discontinuous coating of a semi-solid composition having an ointment-like feel overlying a portion of the first surface of said absorbent substrate.
The absorbent substrate in the dressing of the invention is useful as a passive dispenser of at least one active ingredient. The discontinuous coating is essentially non-adherent to the skin and is useful as an active dispenser of at least one active ingredient.
In a preferred embodiment, the dressing of the invention contains at least one active ingredient intended to provide therapeutic benefit to the skin. In another preferred embodiment, the dressing of the invention contains at least two active ingredients, the first being substantially contained within the absorbent substrate, and a second active ingredient contained substantially within the discontinuous coating.
Also included within the scope of the invention are adhesive bandages comprising a backing material, an adhesive layer and the above-enumerated dressings.